docs: def _find_missing(self, data, return_bool=False):
          """ ???
  
          Parameters
          ----------
          data            : pd.DataFrame()
              Input dataframe.
          return_bool     : bool
              ???
  
          Returns
          -------
          pd.DataFrame()
              ???
  
          """
  
          # This returns the full table with True where the condition is true
          if return_bool == False:
              data = self._find_missing_return_frame(data)
              return data
  
          # This returns a bool selector if any of the column is True
          elif return_bool == "any":
              bool_sel = self._find_missing_return_frame(data).any(axis=0)
              return bool_sel
  
          # This returns a bool selector if all of the column are True
          elif return_bool == "all":
              bool_sel = self._find_missing_return_frame(data).all(axis=0)
              return bool_sel
          
          else:
              print("error in multi_col_how input")